Fifteen awaiting-trial prisoners escaped from police holding cells at the weekend.
Police said the suspects, mostly illegal Mozambicans, escaped by cutting the iron bars from the windows of the cell in Komatipoort, Mpumalanga, on Saturday night when it was raining heavily.
Police spokesman Michael Ngomane said the escape was only discovered on Sunday morning when they went to count the prisoners in the cell.
Police think the inmates used a hacksaw to cut open the window bars.
It is not known how a hacksaw got into the cell.
The five prisoners left behind in the cell, which accommodates 20, told police they were asleep when the other inmates escaped.
Police are not allowed inside the cells late at night, and because of the heavy rains they had difficulty doing night patrols outside.
Ngomane said it would be difficult to track down the suspects once they return to Mozambique.
"We have tried to search for them at the border post, but we did not find anything," he said.
The escaped prisoners face charges of murder, armed robbery, car theft and housebreaking.